Bosch 6-Axis Inertial Measurement Unit for Always-On Future

SAN FRANCISCO — Sensortec, the consumer electronics sensor arm of Bosch, has announced a new integrated low-power sensor platform. Its six-axis inertial measurement unit (IMU) is designed for always-on applications in mobile and the Internet of Things.

“The trend we see is going to IMUs. A lot of companies have standalone accelerometers and gyroscopes; we see high interest in going to combo sensors for a small footprint,” Sensortec CEO Stefan Finkbeiner told EE Times. “If you want to go in a smartwatch, for example, this is very important.”

Sensortec’s BMI160 hub is a three-axis accelerometer and three-axis gyroscope on a 2.5mm x 3mm x 0.8mm footprint. The company is not the first to focus on integrated parts, analyst Gerry Purdy says, noting that hubs are becoming more commonplace.

“System players like Apple or Samsung are looking at how to provide capabilities as part of their ecosystem. Then there are people who believe there’s a market for chipsets and individual entities that can be a feature set or add-on,” Purdy, chief analyst at Compass Intelligence, told us. “If you look at the craze going on with health and fitness with embedded products, the chip level has to integrate these things.”

The IMU’s selling point, particularly with wearables, is its low power consumption. The device consumes 950 microamps while in use and 4 microamps during sleep mode, according to Finkbeiner.

“It has a very low current, around four times less than market average, which gives the opportunity to keep devices always on… for context awareness,” he said, adding that switching sensors on and off causes accuracy loss. “This gives a huge amount of new use cases, which previously weren’t available.”

Low-power accelerometers are now table stakes in the wearables market, says Purdy. The next step will be developing systems that can efficiently power sensor hubs. The BMI160's accelerometer is always on but uses an ASIC interrupt signal to wake the gyroscope from sleep mode.

Finkbeiner says the hub also comes with ASICs to enable smart devices with wearable components, context awareness, and immersive gaming. To send data, however, an external microcontroller is necessary.

Purdy tells us future sensor hubs will likely integrate heart-rate monitors due to the large number of health-related devices driving the Internet of Things explosion. Sensortec had no comment on additional sensors that might be integrated in future platforms.

Not all the sensors need to be on-mode all the time but foresure many applications can get benefit from the low-power consuption of the IMU. Small footing and integration are always good to have in any product.